I just ran Prime95 memory test and it crashed within an hour, which I found really weird, considering everything was perfectly ok a few months ago when I built this PC.
I have all BIOS settings related to memory on auto, performance enhance is set to turbo.
CPU voltage is, I believe, set to normal with -0.045V offset.

Is there anything I could try in advanced voltage settings that could bring memory stability back? I have to point out the Small FFTs test doesn't give any errors at all.

I have to slightly correcy myself: I did have Performance Enhance set to Extreme (which obviously did work in past though). After swithing to Normal, Prime passed well over an hour without problems. I have to test it further, because it still crashes when I use Turbo, which is thedefault value. This is not right.

Make sure you do not use the predefined overclocking modes that the board comes with. Each chip and board is different so it may do things like ramp up the voltage here and there thinking the CPU needs it when it does not.

I didn't touch all that much. My original goal was some reasonable overclock from default speed at stock voltages (or lower), which I kind of achieved after lenghty discussions with cadaveca (thanks again). I extensively tested it and it was stable. Weird...

many possibilities as to what is causing the issue. Could even just be new software. You'll need to test a bit more and get some crashes, and provide the info about those crashes, before we can really assess what's going on.

You aren't running really high clocks, or voltages, and sometimes things have a tendency to "settle in" a bit after first OC as the system gets "used to it", so what you are reporting is relatively normal.

This is seriously weird.
Prime95's "In-place large FFTs" keeps crashing in under an hour (usually much faster, like 30 mins or so), while Small FFTs (which as I understand is stressing CPU the most) can happily pass a few hours.

The original DVID offset was -0.045V, and the Small FFTs test could go without errors even at like -0.055V (wouldn't think it stable at all, but it's interesting). I've been repeating the former test all the way down to -0.020V and then stopped, because the problem must lie elsewhere. But where?
All the other major voltages are set manually to their defaults (VTT=1.050V, PLL=1.800V, IMC=0.925V) just like always. I also tried to set BCLK and multipliers manually (to the same values though), and it didn't do anything as expected.

One more thing I am trying right now is going back to the original offset, but having Performance Enhance option set to normal instead of turbo (what in the hell does it do anyway?). After that I am completely out of ideas. (edit: fail in 6 minutes. fking hell...)

To add to the weirdness.
DVID offset doesn't seem to do anything. I compared min and max values of VCORE in CPU-Z during idle and load, and then switched from -0.045V to pure auto setting, and the voltage was absolutely identical. Just wtf...

Just earlier tonight I had similar problems with my Asus P8Z77-V; after replacing the stock TIM on my H100 with Arctic Silver 5, I noticed that changing the multiplier in BIOS didn't change the clock speed in Windows. After several attempts using every setting available, still the same result - zilch. I had updated to 1805 when it came out a few weeks ago. I remembered reading another post about someone with the same problem who re-flashed the previous BIOS and solved the problem, so I flashed 1708 using USB flashback and now I can change settings.
I think I'll just keep this BIOS until a new one comes out. I never had any problem with 1708 and also my temps seem to be lower.

I switched memory completely for some 2GB piece of shit, and it passed like 9 hours. Could be coincidence, but after plugging my regular memory back in (in different slots now just to give it a go), Prime95 crashed in 22 minutes. I will test this once more. Interesting fact is MemTest passed without problems. Could it be some weird incompatibility?

I think I am fucked. Flashed a lot newer BIOS (which says improves some compatibility as well) and sure enough, Prime95 crashed in minutes.
There's no way in hell I can RMA this since no store gives a flying fuck about what program a random hippie uses for stability testing. They'd throw Memtest at it at most and would charge me for RMAing working product.

I think I am fucked. Flashed a lot newer BIOS (which says improves some compatibility as well) and sure enough, Prime95 crashed in minutes.
There's no way in hell I can RMA this since no store gives a flying fuck about what program a random hippie uses for stability testing. They'd throw Memtest at it at most and would charge me for RMAing working product.

Click to expand...

Christ,

You do not RMA to the store! You call Asus support or whatever manufacture and get an RMA ticket, and send it in. They process the RMA, and they send a replacement back.

Yeah but there are serial numbers written on the invoice from the store I bought the stuff in. I would value that warranty over anything.
What you say is definitely a possibility as well, though.

UPDATE:

I should have friggin' guessed - the dumbass XMP profile! I'll have to set timings manually and experiment with values, but manually setting 1866MHz and having timings on auto doesn't seem to give me any errors.

Nobody mentioned this here but best practice for updating Bios is to set Bios to Default settings before attempting any sort of update/flash. This means no overclock settings.

Since I ran in to a problem once with a UEFI flash, I have taken to disconnecting all HDs and SSDs for this step and setting up Bios or UEFI by resetting after the flash the AHCI, XMP, etc. then rebooting. I then tweak memory and voltage settings, rebooting to see that settings are working, shut down, then reattach the drives. Seems like more work than it should be but it appears to make certain that the flash and settings work without corruptions.

As a side note I have been using a USB drive to flash from. The .bin file you would scroll to (pick from list), if there are more than just the .bin on the USB drive. Some motherboards may want a dedicated/clean source for file and by that I mean a USB with only the .bin file.

1. Reset your UEFI to Optimized Defaults, reboot, enter UEFI and then flash to the new UEFI build.
2. After flash and restart, enter Windows/Linux, then exit and shutdown.
3. Remover the power cord from the power supply, wait thirty seconds, press Power On button to clear any remaining charge, clear CMOS for five seconds, reattach the power cord, power on the system, enter UEFI, set to Optimized Defaults, save and exit.
4. Enter UEFI, set your system to customized settings based on your system configuration (RAID, OC, etc), save and exit.